Method of manufacturing printing plates



Patented Dec. 2, 1941 STATES PAT E TES Jack J- Kessler. c c xo. 111.. nmaaar m United Antoogi'rsaphic Register Co.,

Illin a corporation 4Claims.

This invention relates particularly to a method of manufacturing a' printing plate of the kind v and its backing platewhich serves to attach the plate to a printing press. Printing plates of the cured to a cram backing plate which may besnapped onto a printing cylinder of a press. Such plates have been found extremely useful in print-' ing continuous-form stationery, books, and the like. In printing continuous-form stationery a I l5 rubber molding material and backing plate on the series of duplicate plates are made from the same matrix and must be very accurately positioned on the backing plate, with respect to-itsattaching clips, or otherwise the forms on the printed sta-' tionery will not be in register when they are brought into superposed relation, and registration of such forms is very essential to a good product. Registration is frequently tested by forcing a knife blade through the top form on a printed line and the knife must cut the same line on the underlying terms with an extremely small amount of tolerance.

Thus. it will be understood that it is necessary to make each rubber plate or the exact same length and it is also necessary to position the rubber plate on the backing plate the exact distance from the clips which are subsequently formed on the backing plate. Also -it is necessary to have the ends, on which the clamping bends are made, perfectly parallel to the lines of printed material to insure both vertical and horizontal alignment. Heretoi'ore an attempt Was made to accomplish such alignment by means of actual layout on each plate and was dependent for its accuracy on the skill and good eyesight oi the operator.

The primary object of the present invention is to provide an improved method of forming the rubber printing plate on the backing plate so that proper registration and alignment are obtained mechanically,.that is from fixed guides, so that special skill is not required to obtain this essential feature. By the present invention a slot is formed in the matrix, the slot is used to position a turned end or the backing plate, the turned end is subsequently removed and a clip formed in' mechanical alignment with the opposite end of the plate, and finally the opposite clip is formed in mechanical alignment with the first clip. By following this method, accurate alignment kindshown inthe above patent are usually of molded rubber'firrnlir se.--

.20 the plate.

positioning is carried through thevarious transiers without any danger of errors The invention is illustrated diagrammatically I in a preferred embodiment in the accompanying '5 drawing, innwhich I Figure lis a sectional view showing the type form locked. up in a chase between two bearer members; Figure 2, a sectional view-showing how "thematrix isformed from the type; Figure 3, a .10, side elevational view of the metal backing plate having-its end portion turned up to fit into the slotted groove formed in the matrix; Figure .4, a bottom plan view of the backingplate shown in Figure 3 ;Figure 5, a sectional view showing the matrix; and Figure 6, a sectional view. of the completed plate, showing by dotted-lines how the turned end or guide flange oi, thebacklng-plate is cut ofi and the clips are formed at theends o! In the embodiment illustrated. an area'oi type I is placed between an ordinary bearer member 8 ends special bearer member 9 and locked up between the jaws ll! of a chase. The special bearer member 9 is provided with a groove or slot H which is very accurately cut so as to be parallel to the lines of type locked up in the chase.

' After the typehas been locked up, a proof copy is madeirom the type and whatever adjustments or corrections that are found necessary must be made. Subsequently a straight edge metal insert I2 is inserted in the slot u to formal! aligning slot or groove in the matrix in the subsequent molding operation. It is preferable to have the member I! removable so thatritwill not cut .or

interfere with the inking roll when proot iswbeing made. As shown inFigure 2,'the assembly, in' Figure l is inverted and an impressionis made in the matrix 13 which preierably is av thermoplastic. material. By the application of heatjand ipressure the matrix I 3 is-thusiormed enaaztee A properly cured is ready to receive -'-the '-rubbe'rous molding material}! and backingplate 15. v

The brass backing plate, illustrated; in;

and "brought into s perposed relation with its flange 3 and 4; preferably ,isa thin 'brass sheet. inthe", form of a very. accuratelyqmeasured irectangla, I Q

l6 placed in the slot I! provided in the matrix.

By the application of heat and pressure the rubber is then cured on the matrix and in'that operation becomes adhered securely to the backing plate throughithe medium of the attaching fabric, the rubber flowing into the fabric and the fabric in turn becoming cemented securely to the backing plate. The combined rubber plate and backing plate is then removed from the matrix and the matrix is ready to be used in forming additional identical plates.

It is possible to form one of the attaching clips utilizing the flange, but preferably the backing plate is placed in a shearing machine with its edge I8 in contact with a fixed guide and the flanged portion I8 is sheared ofi along a line exactly parallel to the edge [8. The plate is then removed to a forming machine where the edge I8 is placed against a mechanical guide and the V-shaped clip I9 is struck from the material on the opposite end. The plate is thenreversed and using the clip IQ for a guide, a clip 20 is formed.

As will be readily understood, it is necessary to work between narrow limits in forming the plates. The transversely extending clips I! and 20 must be exactly parallel and a variation in their spacing of a sixty-fourth of an inch would prevent their proper attachment to a'printing roll which subsequently rotates athigh speed. If one of the printing plates should become loose while the machine is operating, severe damage to the press might result. However, by practicing'the present method, a highde'gree of accuracy is'assured andthe costof producing the plates is greatly reduced. j

The foregoing detailed description has been given for clearness of understanding only and no unnecessary limitations should be understood therefrom for some modifications will be obvious to those skilled in the art.

I claim:

1. The method of registering a printing plate on a backing plate which comprises: forming a matrix with a slot aligned with respect to the type impression in the matrix; placing rubberous molding material on the matrix and superposing a metal rectangular backing plate of proper size having an integrally formed perpendicularly disposed aligning flange extending into the matrix slot; curing the rubberous molding material and simultaneously securing it to the backing plate through the application of heat and pressure; removing the combined printing and backing plate from the matrix; forming one end of the backing plate into an attaching clip mechanically aligned with respect to the opposite end of the backing plate; and then forming another clip, opposite from the first clip and mechanically aligned with respect thereto.

- 2. The method as specified in claim 1, including th step of cutting ofi the aligning flange of thebacking plate prior to forming the first clip.

3. The method of registering a printing plate on a backing plate which comprises: locking up type between bearer members in a chase, one of th bearer members having an upwardly extending straight edge portion; forming a matrix on said type and straight edge so that the latter will form an aligning slot in said matrix; placing rubberous molding material on the matrix and superposing a metal rectangularbacking plate of proper size having an integrally formed perpendicularly disposed aligning flange extending into the matrix slot; curing the rubberous molding material and simultaneously securing it to the backing plate through the appplication of heat and pressure; removing the combined printing and backing plate from the matrix; forming one end of the backing plate into an attaching clip mechanically aligned with respect to the opposite endof the backing plate; and then forming another clip, opposite from the first clip and. mechanically aligned with respect thereto.

4. The method of registering a rubber printing plate on a backing plate which comprises: locking up the type between bearer members in a chase, one of said bearer members having a slot; placing a thin metal insert in said slot so that said insert extends slightly above the top of the bearer member; forming a matrix against said type and insert; removing said matrix and insert; placing a sheet of rubberous material on said matrix and superposing a backing plate with an aligning fiange'extending into the slot in the matrix; curing the rubber and securing it to the backing plate by the application of heat and pressure; removing the assembly from the matrix and cutting off the flange portion at a mechanically fixed distance from the opposite edge of the backing plate; forming an attaching clip on the trimmed edge of the plate in mechanical alignment with the opposite edge portion; and

forming a clip on the opposite end of the plate at mechanically measured distance from the first clip.

JACK J. KESSLER. 

